Compress an image under 100KB — without losing quality

Why 100KB is such a common limit

100KB is the sweet spot for image uploads on most government and corporate portals: it's small enough to keep their servers light, yet large enough that a properly compressed photo still looks decent.

Common forms requiring under 100KB images:

• University admission portals (resume, photo, signature)
• Driving license applications
• Tax filing platforms (signature, address proof)
• Banking KYC uploads
• Online competitive exam registrations

The two ways to shrink an image

There are only two ways to make an image smaller in file size:

1. Reduce quality — re-save the image at a lower JPEG quality. The image looks the same to the eye but stores fewer details.
2. Reduce dimensions — make the image smaller in pixels (e.g. from 4000×3000 to 1000×750).

For most cases, lowering quality is enough. Reducing dimensions only becomes necessary when you need extreme compression (like 20KB or smaller).

The fastest way: use a smart binary search

Standard photo editors give you a quality slider (0–100). You drag, save, check size, drag again. Repeat 10 times until you hit the target.

Kodotools automates this. We use binary search — start at quality 50, see if it's too big or too small, adjust, repeat until we hit the exact target. It's typically 10x faster than manual sliders, and lands within ~2% of your target.

All of it happens inside your browser using the HTML5 Canvas API. Your image never leaves your device.

Step-by-step

1. Open kodotools.com/image-compression
2. Drop your image (JPG, PNG, WebP, or HEIC)
3. Click the 100 KB preset button
4. Hit "Compress all" — the tool finishes in a second
5. Click the download button to save the compressed JPG

Tips for keeping quality high under 100KB

• Crop unnecessary background — less area means more bytes for the part you care about.
• Resize before compressing — if your photo is 4000px wide and you only need 800px, resize first.
• Avoid PNG for photos — JPG always wins for photographs. PNG is best for screenshots and graphics with text.
• Aim for the limit, not below — if the form allows up to 100KB, aim for 90KB. Don't waste quality going to 30KB.

Common KB targets at a glance